best way to upgrade raid1

the setup:

dell precision 670, with two 250gb sata drives, handled by the onboard cerc 2s sata raid controller.

the drives are in one raid1 array, one logical drive of 250gb (232gb usable).  windows xp x64 installed and working fine.

the board only has 2 sata ports.

i have two new 2TB drives, i want to have the two 2TB drives in one array mirrored, 2TB usable space, and have a CLONE of the original array, so i dont have to reinstall everything.

the original 250gb drives and array can go away when done.  

a good backup exists (cloned to a usb drive)

so - what's the best way to get this done?

what i am about to do is:
1. remove one of the 250gb drives (degrade the array) and install one 2TB drive
2. boot to windows, casperXP the logical drive onto the 2TB drive
3. reboot, remove the 250gb drive, put in the 2nd 2TB drive
4. control-a into the sata raid bios, and tell it to create a new array of the 2TB drives

will it understand i want to mirror the 1st 2TB (which will already be cloned from the original 250gb drives) drive onto the empty second 2TB drive?

or is there a better way?

LVL 24
B HAsked:
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all your techniques put your data in various levels of disk.

for one thing, they all put you proverbial eggs in a single basket.  lose a drive and you lose everything. lose a  block and you have partial loss.

you need to raid protect your backup. buy either a 2nd raid controller or one with 4 ports. caspar to that after you initialize the new disks... then change the drive order.

done, with near zero risk.
Your sequence basically makes sense.

Alternately, you could remove one of the 250GB drives and rebuild the array onto the new 2TB drive. Then, after the rebuild, replace the second 250GB drive and rebuild again.


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B HAuthor Commented:
i do see the risk, but i have a complete sector by sector backup on an external usb drive that is not being touched, so i accept the risk.

i put in one of the 2TB drives, and booted... casper and windows both dont see that it exists (altho the control-a cerc 2s bios does see it just fine.

windows boots fine, just doesnt see the drive - neither does device manager or disk manager... so i figure the cerc bios isnt sending it to windows as available.

what are the steps to rebuild onto the 2TB drive?  
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B HAuthor Commented:
the cerc bios identifies both drives correctly, as 1962.9GB each

but when i go to create a container out of them, with both present, these are my only options:

raid0 stripe 1862gb total
raid1 mirror 1023gb total - and it shows the drives as 1TB each

what gives?
The CERC 2s SATA controller is an unfortunate orphaned RAID controller that was also present, and unloved, in the PowerEdge 420SC, as well as other systems.

There are various problems with it and it is poorly supported by Dell, especially for any configuration that Dell did not actually ship.

Specifically, CERC 2s SATA is not supported for Windows 7, or Server 2008 (or R2).

I would not be surprised in the least to find that it only supports drives up to 1TB.

Your process to migrate is still sound, but your RAID controller may not be. Since the CERC 2s is essentially software RAID, in the same way as the Intel matrix storage manager, you gain little that a good backup would not provide, and lose a fair bit of performance in the process.

Given the typical specs of your system, if you need less than 8GB of memory, even a low end Dell (e.g. Vostro 230) will give you better performance and I know it supports 2x2TB RAID1.
B HAuthor Commented:
hmm.. good info...

without buying a new machine, what would be the best course of action?

i want the most available usage space, but if a drive fails i want it to limp long enough for me to replace the bad drive

i'm ok with slower performance - so that's not a problem... i just dont want to be restoring everything for hours unexpectedly.

so...... i see i can turn off raid on this cerc garbage, and let windows manage the drives...  is there a course of action to do this, let windows see both drives, and let windows handle the mirroring?

i understand they'll both need to be dynamic disks, but you can't supposedly change a boot disk to dynamic either

what's the best way out?

i'll go check for a firmware update for the cerc, that i doubt exists
B HAuthor Commented:
well, casperxp refuses to clone onto the 2tb drive, machine locks up completely.

found a bios update for the cerc which specifically fixes the lockup when things try to directly access the mbr, clone is running now

found a dell article which says it supports up to a maximum of 2TB drives, which is good i guess

after the clone is done (2 hours) i'll try to swap in the other 2TB and say make me a mirror... hopefully it will actually give me a 2TB mirror (well 1.8TB mirror anyway)
When was the last time that you actually had a drive fail?  My criteria for mirroring is the difficulty in replacing the lost data rather than time taken to reinstall. I find that I spend more time preparing for failure than I would installing a new OS after failure. This is OK if the data is not recoverable, but is not a good use of time if the issue is just the time it takes to reinstall a program.

One half-measure is to image the drive occasionally (as a backup) that you can then just boot if the worst happens to the running drive.

You won't be able to run a software mirror in XP64, though Windows 2003 x64 Server does support it. You should have no trouble turning a boot drive into a dynamic disk, as long as you don't dual boot.
B HAuthor Commented:
i see...  so if this clone>array>mirror>boot thing doesnt work...  that'll have to be the way to go... i'll just schedule casperxp to do nightly clones to the second 2TB disk (will take 5-10 minutes per night after first one completes)

i see that way we can just switch the boot device to the live one, if one fails.  i like the idea of a mirror so it's on the fly though, hope it works.

it's not my machine, it's for a client who filled his previous 250gb and can't afford downtime when his own clients are relying on his stuff to work

i see failed drives all the time, but usually in raid5 with hotplug drives so it's nothing to deal with.... or on the other hand, home users with a failed drive and no backup :)

RAID1 has another benefit that you are not considering.  It protects against data loss due to an unreadable block or blocks.   Considering that the typical high-density SATA disk has tens of thousands of spare blocks, then this should be anecdotal evidence that bad blocks occur quite often.

That is why RAID firmware has such things as consistency checks, or repairs.  

Ever get an error saying the computer can't read a file or block?  RAID 1/5/10 protects against this.  If disk A can't supply the data, then disk B does, and then the controller instructs A to use a reserved sector and disk B data repairs it.

You are going down a slippery slope with this design. Statistically speaking, you have a 100% probability of partial data loss.  Do the right thing and if you must, just get a cheap external enclosure with a built-in RAID1 controller.   spend an extra $20 or so, and you can get one with eSATA, and it will probably faster then the CERC you have now.
B HAuthor Commented:
all i want is raid1, i understand you completely... i'm trying my best to make raid1 happen, just on bigger drives

the idea of a raid1 external enclosure though, i dont think i want my operating system/boot drives/mirror hanging out around the outside world... they're nice and happy inside their little hard drive shelves inside the case (which locks)

If it's a client system, then RAID1 is probably the best idea but you have two problems:

1) CERC 2s doesn't support the full drive capacity (might not be a show stopper)
2) XP64 doesn't support Software RAID1

Reinstalling with software RAID on Windows Server solves both issues, as does just settling for less space (1.8GB). The latter is simpler and likely sufficient.

I would suggest that you just rebuild the array with the 2TB drive and then do it again with the other 2TB drive. That way you maintain a bootable copy (the removed half of the mirror) until you know that everything works.

B HAuthor Commented:
this is exactly what i ended up doing.  i thought i closed this question out, but today it came back as abandoned (?!)
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